Continuous production of a near infrared absorbing chromophore

Abstract

The nickel dithiolene complex-type near-infrared chromophore, nickel bis-(1,2-diisopropylthioethane-1,2-dithiolene), was synthesized in three reaction steps and applied to a near-infrared cutoff filter for PDP TV. A microreactor was employed in the strong exothermic reaction of 2-propanethiol and oxalyl chloride. A 90% yield of SS'-diisopropyl dithiooxalate was obtained with a 75% reduction in solvent usage. Thionation of S,S'-diisopropyl dithiooxalate with the use of tetraphosphorus; decasulfide and aluminum hydroxide provided a clean dithiolene feed for the next continuous step. The final product was efficiently produced in a microreactor and a tubular reactor in series using nickel chloride solution and dithiolene synthesized from thionation in a batch reactor.